Atomic layer deposition of silicon carbon nitride based materials

ABSTRACT

A process for depositing a silicon carbon nitride film on a substrate can include a plurality of complete deposition cycles, each complete deposition cycle having a SiN sub-cycle and a SiCN sub-cycle. The SiN sub-cycle can include alternately and sequentially contacting the substrate with a silicon precursor and a SiN sub-cycle nitrogen precursor. The SiCN sub-cycle can include alternately and sequentially contacting the substrate with carbon-containing precursor and a SiCN sub-cycle nitrogen precursor. The SiN sub-cycle and the SiCN sub-cycle can include atomic layer deposition (ALD). The process for depositing the silicon carbon nitride film can include a plasma treatment. The plasma treatment can follow a completed plurality of complete deposition cycles.

REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/196,985, filed on Jun. 29, 2016, which is a divisional ofU.S. patent application Ser. No. 14/566,491, filed on Dec. 10, 2014, nowU.S. Pat. No. 9,401,273, which claims priority to U.S. ProvisionalApplication No. 61/914,882, filed Dec. 11, 2013, each of which is herebyincorporated by reference in its entirety.

BACKGROUND Field

The present disclosure relates generally to the field of semiconductordevice manufacturing and, more particularly, to deposition of siliconnitride based films.

Description of the Related Art

As the physical geometry of semiconductor devices shrinks, depositionprocesses for forming silicon nitride based films on three-dimensionalstructures having high aspect ratios is desired. Additionally, it isdesirable to be able to deposit silicon nitride based films thatdemonstrate an advantageous etch selectivity with respect one or moreother materials in the formation of a semiconductor device, and/or adesirable etch rate in a dry etch and/or wet etch process.

Deposition of silicon nitride based films having desired characteristicsby atomic layer deposition (ALD) processes using reduced thermal budgetscan be difficult (e.g., such as at reduced temperatures, including attemperatures of less than about 600° C.). Silicon nitride based filmsdeposited by conventional processes (e.g., silicon nitride based filmdeposited using plasma enhanced ALD (PEALD)) performed at reducedtemperatures may result in films having undesirably low conformalityand/or undesirably low film quality inside three-dimensional structures.The low conformality and/or reduced film quality may be due to theanisotropic nature of direct plasmas. Silicon nitride based films formedusing conventional methods may also undesirably demonstrate high etchrates and/or have low etch selectivity to another different material ina semiconductor device (e.g., a thermal silicon oxide material, TOX),such that the silicon nitride film cannot withstand one or moresubsequent thermal silicon oxide etch steps used in the devicefabrication process. For example, the wet etch rate (WER) in diluteaqueous hydrofluoric acid solution (e.g., dHF, or aqueous hydrofluoricacid solution having a concentration of about 0.5 weight %) of a siliconnitride based film deposited using conventional means at temperatures ofbelow about 600° C. typically are too high, for example in comparison toanother layer in the film stack (e.g., a TOX layer).

SUMMARY

Processes for depositing silicon carbon nitride films on a substrate caninclude a plurality of complete deposition cycles, each completedeposition cycle comprising a SiN sub-cycle and a SiCN sub-cycle, wherethe SiN sub-cycle can include alternately and sequentially contactingthe substrate with a silicon precursor and a first nitrogen precursor(also referred to as a SiN sub-cycle nitrogen precursor). The SiCNsub-cycle can include alternately and sequentially contacting thesubstrate with a precursor comprising silicon and carbon and a secondnitrogen precursor (also referred to as a SiCN sub-cycle nitrogenprecursor). In some embodiments, the process can include exposing thesilicon carbon nitride film to a plasma treatment, for example toimprove one or more film qualities. In some embodiments, the plasmatreatment follows the completion of the plurality of complete depositioncycles.

In some embodiments methods for improving film properties of a siliconcarbon nitride film can include exposing the silicon carbon nitride filmto a hydrogen-containing plasma treatment process. A reactant gas forthe hydrogen-containing plasma can comprise hydrogen gas (H₂) and anoble gas. In some embodiments, a reactant gas for thehydrogen-containing plasma consists of hydrogen gas (H₂) and a noblegas. In some embodiments, the noble gas can be argon (Ar).

In some embodiments, processes for forming silicon carbon nitride filmscan include depositing a silicon carbon nitride film on a substrate andtreating the silicon carbon nitride film to a hydrogen-containingplasma. In some embodiments, depositing the silicon carbon nitride filmincludes performing at least one SiCN deposition cycle, where the atleast one SiCN deposition cycle includes alternately and sequentiallycontacting the substrate with a precursor comprising silicon and carbon,and a SiCN deposition cycle nitrogen precursor.

For purposes of summarizing the invention and the advantages achievedover the prior art, certain objects and advantages are described herein.Of course, it is to be understood that not necessarily all such objectsor advantages need to be achieved in accordance with any particularembodiment. Thus, for example, those skilled in the art will recognizethat the invention may be embodied or carried out in a manner that canachieve or optimize one advantage or a group of advantages withoutnecessarily achieving other objects or advantages.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments will becomereadily apparent to those skilled in the art from the following detaileddescription having reference to the attached figures, the invention notbeing limited to any particular disclosed embodiment(s).

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure are described with reference to the drawings of certainembodiments, which are intended to illustrate certain embodiments andnot to limit the invention.

FIG. 1 shows an example of a process for forming a silicon carbonnitride material on a substrate.

FIG. 2 is a graph showing growth rates for examples of silicon carbonnitride (SiCN) films.

FIG. 3 is a table providing the composition of examples of siliconcarbon nitride (SiCN) films.

FIG. 4 is a graph showing etch rate performance of examples of siliconcarbon nitride (SiCN) films.

FIG. 5 shows an example of another process for forming a silicon carbonnitride material on a substrate.

FIG. 6 is a graph showing changes in thickness of silicon nitride (SiN)films when exposed to a wet etchant, where the SiN films have beensubjected to different plasma treatment processes.

FIG. 7 is a graph showing changes in thickness of silicon carbon nitride(SiCN) films when exposed to a wet etchant, where the SiCN films havebeen subjected to different plasma treatment processes.

FIG. 8 is a graph showing changes in thickness of silicon carbon nitride(SiCN) and silicon nitride (SiN) films when exposed to a wet etchant,where the SiCN and SiN films have been subjected to a plasma treatmentprocess.

FIG. 9 is a graph showing changes in thickness of silicon carbon nitride(SiCN) films when exposed to a wet etchant, where the SiCN films havebeen subjected to a plasma treatment process.

FIGS. 10A and 10B are field emission scanning electron microscopy(FESEM) image of a cross-section view of trench structures coated by asilicon nitride (SiN) film before and after being exposed to a wetetchant.

FIGS. 11A and 11B are field emission scanning electron microscopy(FESEM) image of a cross-section view of trench structures coated by asilicon carbon nitride (SiCN) film before and after being exposed to awet etchant.

FIG. 12 is a field emission scanning electron microscopy (FESEM) imageof a cross-section view of trench structures coated by a silicon carbonnitride (SiCN) film after being exposed to a wet etchant.

FIG. 13 is a table providing the composition of silicon carbon nitride(SiCN) films.

FIG. 14 is a table providing the composition of silicon carbon nitride(SiCN) films.

DETAILED DESCRIPTION

Although certain embodiments and examples are described below, those ofskill in the art will appreciate that the invention extends beyond thespecifically disclosed embodiments and/or uses and includes obviousmodifications and equivalents thereof. Thus, it is intended that thescope of the invention herein disclosed should not be limited by anyparticular embodiments described below.

In some embodiments, a process of fabricating a silicon nitride basedmaterial containing carbon, or a silicon carbon nitride (SiCN) film,having desirable characteristics (e.g., desired conformality and/orreduced wet etch rate in dilute aqueous hydrofluoric acid solution) caninclude a thermal atomic layer deposition (ALD) process performed atreduced temperatures (e.g., at less than about 600° C., including about300° C. to about 600° C., and about 400° C. to about 500° C.). In someembodiments, addition of carbon into a silicon nitride film canadvantageously provide a film having desirable characteristics, such asa film demonstrating a reduced wet etch rate while maintaining desiredconformality with respect to underlying three-dimensional structures,and without or substantially without increasing a k-value of the film.In some embodiments, addition of carbon into a silicon nitride film canbe achieved by using a precursor comprising silicon and carbon in thefilm deposition process. In some embodiments, a film wet etch rate of asilicon carbon nitride film can be adjusted by adjusting the number ofcycles of the deposition process which includes the precursor comprisingsilicon and carbon. For example, a thermal ALD process can include anumber of cycles which includes the precursor comprising silicon andcarbon to achieve a desired carbon content in the deposited siliconcarbon nitride film, so as to facilitate the desired wet etchperformance. In some embodiments, the selection of the precursorcomprising silicon and carbon may facilitate formation of a siliconcarbon nitride film having desired wet etch performance. In someembodiments, precursors of the thermal ALD process can have sufficientlyhigh vapor pressures such that the process can be carried out in a batchreactor for increased throughput.

In some embodiments, a process of fabricating a SiCN film can include acombination of a thermal ALD process and a plasma treatment. Forexample, the process can include a thermal ALD process followed by aplasma treatment. The number of repetitions of the thermal ALD processnumber of repetitions of the plasma treatment, and/or the processparameters of the thermal ALD process and/or the process parameters ofthe plasma treatment, can be optimized to provide a SiCN film havingdesired characteristics (e.g., including formation of films havingdesired characteristics on three-dimensional (3-D) structures havingaspect ratios of at least about 6).

In some embodiments, SiCN films treated by a plasma treatment processhave very low to negligible dHF etch rates. In some embodiments, one ormore plasma treatment units can be combined in a cluster tool with oneor more batch reactors for performing thermal ALD processes,facilitating integration of the SiCN film formation process.

Silicon nitride based layers are widely used in semiconductormanufacturing. For example, silicon nitride based films can be a part ofsemiconductor devices, and/or fabrication processes for varioussemiconductor devices, including for example various transistors (e.g.,FinFETs). In some embodiments, silicon nitride films can be deposited ona three-dimensional feature such as a spacer material on a gate featureof a transistor, used as a sacrificial layer and/or as an etch stoplayer, in the fabrication process.

In some embodiments, one or more processes described herein can be usedto form a silicon carbon nitride film having a desirable wet etch raterelative to that of thermally grown silicon oxide (TOX). In someembodiments, a silicon carbon nitride film formed according to one ormore processes described herein can demonstrate a wet etch rate ratio(WERR) relative to TOX of less than about 1:1, more preferably less thanabout 1:2. In some embodiments, a silicon carbon nitride film formedaccording to one or more processes described herein can demonstrate aWERR relative to TOX of about 1:5 or less, about 1:10 or less, or about1:20 or less. For example, a wet etch rate of thermally grown siliconoxide in a dilute aqueous hydrofluoric acid solution (e.g., dHF, anaqueous HF acid solution having a concentration of about 0.5 weight %)can be about 2 nanometers per minute (nm/min) to about 3 nm/min. Suchsilicon carbon nitride films may be used, for example, in gate spacerapplications. In some embodiments, it can be advantageous for a gatespacer comprising the silicon carbon nitride film to withstand orsubstantially withstand an etch step for removing a thermal oxide layerhaving a certain thickness, including a thermal oxide layer having athickness of about 1 nanometer (nm) to about 10 nm, about 4 nm to about10 nm, about 1.5 nm to about 5 nm, or about 2 nm to about 3 nm. In someembodiments, a silicon carbon nitride film formed according to one ormore processes described herein can withstand or substantially withstandan etch step for removing a thermal oxide layer having a thickness ofgreater than 10 nm.

Deposition of Silicon Carbon Nitride Films

In some embodiments, a process of depositing a silicon carbon nitride(SiCN) film comprises both a deposition process for depositing a siliconnitride (SiN) component (e.g., a number of deposition cycles fordepositing a SiN, such as a number of SiN sub-cycles), and a depositionprocess for adding a carbon component to the growing film (e.g., anumber of deposition cycles which includes a precursor comprisingsilicon and carbon, such as a number of SiCN sub-cycles). For example, aprocess for fabricating a SiCN film can include a number of completecycles, each complete cycle including a number of SiN sub-cycles and anumber of SiCN sub-cycles. In some embodiments, a process of fabricatinga SiCN film having desired characteristics can include a number ofcomplete cycles, where each complete cycle includes a ratio of a numberof SiN sub-cycles to a number of SiCN sub-cycles optimized to obtain thedesired characteristics, such as wet etch rate. The ratio of the numberof SiN sub-cycles to the number of SiCN sub-cycles of a complete cyclecan be expressed as having a percentage of SiCN sub-cycles (e.g., a SiCNsub-cycle percentage or a SiCN deposition sub-cycle percentage). Forexample, a complete cycle for depositing a SiCN film including onedeposition cycle for depositing a SiN component (e.g., one SiNsub-cycle) and four deposition cycles for adding a carbon component(e.g., four SiCN sub-cycles) can have a SiCN sub-cycle percentage ofabout 80%. In some embodiments, a complete cycle can have SiCN sub-cyclepercentage of about 10% to about 100%, including about 25% to about 98%,about 50% to about 95%, and about 75% to about 85%.

In some embodiments, one or more parameters of a SiN sub-cycle can bedifferent from that of another SiN sub-cycle. In some embodiments, oneor more parameters of a SiN sub-cycle can be similar to or the same asthat of another SiN sub-cycle such that the SiN sub-cycles are performedunder similar or identical process conditions. In some embodiments, oneor more parameters of a SiCN sub-cycle can be different from that ofanother SiCN sub-cycle. In some embodiments, one or more parameters of aSiCN sub-cycle can be similar to or the same as that of another SiCNsub-cycle such that the SiCN sub-cycles are performed under similar oreven identical process conditions.

In some embodiments, a silicon carbon nitride film formed according toone or more processes described herein is not a nanolaminate film. Thatis, separate and distinct layers may not be visible within the siliconcarbon nitride film. For example, a continuous or substantiallycontinuous silicon carbon nitride film may be formed.

As described above, in some embodiments, a process for forming a siliconcarbon nitride (SiCN) film of a desired thickness and/or composition caninclude an ALD deposition process (e.g., a SiN deposition sub-cycleand/or a SiCN deposition sub-cycle can comprise an ALD process). ALDtype processes are based on controlled surface reactions that aretypically self-limiting. Gas phase reactions are avoided by contactingthe substrate alternately and sequentially with precursors, although insome instances, some overlap is possible. Vapor phase precursors areseparated from each other in the reaction chamber, for example, byremoving excess precursors and/or precursor byproducts from the reactionchamber between precursor pulses. For example, an ALD deposition processcan include contacting a substrate with a first precursor (e.g., asilicon precursor for a SiN deposition sub-cycle or a precursorcomprising silicon and carbon for a SiCN deposition sub-cycle) such thatthe first precursor adsorbs onto the substrate surface, and contactingthe substrate with a second precursor (e.g., a nitrogen precursor of aSiN deposition sub-cycle or a nitrogen precursor of a SiCN depositionsub-cycle). Exposure of the substrate to the first precursor and thesecond precursor can be repeated as many times as required to achieve afilm of a desired thickness and composition. Excess precursors may beremoved from the vicinity of the substrate, for example by evacuatingthe reaction chamber and/or purging from the reaction space with aninert gas, after each contacting step. For example, excess reactantsand/or reaction byproducts may be removed from the reactor chamberbetween precursor pulses by drawing a vacuum on the reaction chamber toevacuate excess reactants and/or reaction byproducts. In someembodiments, the reaction chamber may be purged between precursorpulses. The flow rate and time of each precursor, is tunable, as is thepurge step, allowing for control of the dopant concentration and depthprofile in the film.

Each cycle of an ALD process can include at least two distinct processesor phases. The provision and removal of a precursor from the reactionspace may be considered a phase. In a first process or phase of an ALDprocess of a SiN deposition sub-cycle, for example, a first precursorcomprising silicon is provided and forms no more than about onemonolayer on the substrate surface. This precursor is also referred toherein as “the silicon precursor” or “silicon reactant.” In a secondprocess or phase of the ALD process of a SiN deposition sub-cycle, forexample, a second precursor comprising a nitrogen-containing compound isprovided and reacts with the adsorbed silicon precursor to form SiN.This second precursor may also be referred to as a “nitrogen precursor”or “nitrogen reactant.” As described herein, the second precursor maycomprise ammonia (NH₃) and/or another suitable nitrogen-containingcompound that is able to react with the adsorbed first reactant underthe process conditions. Preferably the reaction leaves a terminationthat is further reactive with the first precursor or another precursorfor a different phase. Additional processes or phases may be added andphases may be removed as desired to adjust the composition of the finalsilicon carbon nitride (SiCN) film. In some embodiments, the additionalprocesses or phases can include one or more precursors different fromthat of the first and second process or phase. For example, one or moreadditional precursors can be provided in the additional processes orphases. In some embodiments, the additional processes or phases can havesimilar or identical process conditions as that of the first and secondprocess or phase. In some embodiments for a silicon nitride (SiN)deposition sub-cycle, one or more deposition sub-cycles typically beginswith provision of the silicon precursor followed by the nitrogenprecursor. In some embodiments, one or more deposition sub-cycles beginswith provision of the nitrogen precursor followed by the siliconprecursor. One or more of the precursors may be provided with the aid ofa carrier gas, such as nitrogen (N₂), argon (Ar) and/or helium (He). Insome embodiments, the carrier gas may comprise another inert gas.

In some embodiments, in a first process or phase of an ALD process of aSiCN deposition sub-cycle, for example, a first precursor comprisingsilicon and carbon is provided and forms no more than about onemonolayer on the substrate surface. This precursor is also referred toherein as “the precursor comprising silicon and carbon” or “the reactantcomprising silicon and carbon.” In a second process or phase of the ALDprocess of a SiCN deposition sub-cycle, for example, a second precursorcomprising a nitrogen-containing compound is provided and reacts withthe adsorbed precursor comprising the silicon and carbon to form SiCN,thereby introducing carbon into the silicon nitride film. This secondprecursor may also be referred to as a “nitrogen precursor” or “nitrogenreactant.” As described herein, the second precursor may compriseammonia (NH₃) and/or another suitable nitrogen-containing compound. Thenitrogen precursor of the SiCN deposition sub-cycle may be the same asor different from a nitrogen precursor of the SiN deposition sub-cycle.Additional processes or phases may be added and phases may be removed asdesired to adjust the composition of the final film. In some embodimentsfor depositing a silicon carbon nitride (SiCN) film, one or more SiCNdeposition sub-cycles typically begins with provision of the precursorcomprising the silicon and carbon followed by the nitrogen precursor. Insome embodiments, one or more deposition sub-cycles begins withprovision of the nitrogen precursor followed by the precursor comprisingthe silicon and carbon. One or more of the precursors of the SiCNsub-cycle may be provided with the aid of a carrier gas, such asnitrogen (N₂), Ar and/or He. In some embodiments, the carrier gas maycomprise another inert gas.

FIG. 1 shows a flow chart of an example of a process 100 for forming asilicon nitride film comprising carbon (e.g., a SiCN film) on asubstrate. In some embodiments the process is a thermal ALD process. Theprocess 100 can include a complete cycle 102 having a SiN sub-cycle 104.In some embodiments, the process 100 includes a second sub-cycle to addcarbon components to the film. As shown in FIG. 1, the process 100 caninclude a SiCN sub-cycle 110 for adding carbon components to the growingSiCN film. In some embodiments, the SiN sub-cycle 104, SiCN sub-cycle110, and/or the complete cycle 102 can be repeated a number of times toform a SiCN film having a desired composition and/or thickness. Theratio of the SiN sub-cycle 104 to the SiCN sub-cycle 110 can be variedto tune the concentration of carbon in the film and thus to achieve afilm with desired characteristics. For example, the number of times SiCNsub-cycle 110 is repeated relative to the number of times the SiNsub-cycle 104 is repeated can be selected to provide a SiCN film withdesired characteristics (e.g., desired wet etch rate).

The SiN sub-cycle 104 can include blocks 106 and 108. In block 106, thesubstrate can be exposed to a silicon reactant. In block 108, thesubstrate can be exposed to a nitrogen reactant. In some embodiments,SiN sub-cycle 104 can be repeated a number of times (e.g., a number ofrepetitions of the blocks 106 followed by 108). In some embodiments,block 106 or block 108 can be repeated a number of times beforeperforming one or more times the other block. For example, block 106 canbe repeated a number of times before performing block 108.

In some embodiments pulses of the silicon precursor for exposing thesubstrate to the silicon precursor and pulses of nitrogen precursor forexposing the substrate to the nitrogen precursor are separated by a stepof removing excess silicon precursor from the reactor (not shown). Insome embodiments excess nitrogen precursor is removed prior to repeatingthe SiN sub-cycle 104. In some embodiments, the SiN sub-cycle 104 is anALD process. In some embodiments, the pulses of the silicon and nitrogenprecursor may at least partially overlap. In some embodiments, noadditional precursors are provided to the reaction chamber eitherbetween blocks 106 and 108, or before starting blocks 106 and 108.

The SiCN sub-cycle 110 for introducing a carbon component into thesilicon nitride film can include blocks 112 and 114. In block 112, thesubstrate can be exposed to a precursor comprising silicon and carbon.In block 114, the substrate can be exposed to a nitrogen precursor. Insome embodiments, SiCN sub-cycle 114 can be repeated a number of times.In some embodiments, block 112 or block 114 can be repeated a number oftimes before performing one or more times the other block. For example,block 112 can be repeated a number of times before performing block 114.

In some embodiments excess nitrogen precursor is removed prior torepeating the SiCN sub-cycle 110. In some embodiments, excess precursorcomprising the silicon and carbon from block 112 can be removed prior toexposing the substrate to the nitrogen precursor in block 114. In someembodiments, the SiCN sub-cycle 110 is an ALD process. In someembodiments, the pulses of the precursor comprising silicon and carbonand of the nitrogen precursor may at least partially overlap. In someembodiments, no additional precursors are provided to the reactionchamber either between blocks 112 and 114, or before starting blocks 112and 114.

In some embodiments, a silicon carbon nitride film formed according toprocess 100 described herein is a not a nanolaminate film. For example,distinct and separate layers within the deposited SiCN film are notvisible, such that the SiCN film is a continuous or substantiallycontinuous film.

A variety of silicon precursors may be suitable. In some embodiments, asuitable silicon precursor in a process for depositing a silicon nitridefilm can include at least one of silicon halides, silicon alkylamines,silicon amines and/or silanes (e.g., including silanes comprising one ormore alkyl groups). For example, a suitable silicon precursor caninclude a silicon chloride. In some embodiments, a silicon precursor caninclude a halosilane. In some embodiments, a silicon precursor caninclude an alkyl silicon compound comprising a halide. In someembodiments, a silicon precursor can be alkyl silane. In someembodiments, a silicon precursor can include octachlorotrisilane(Si₃Cl₈, OCTS). In some embodiments, a silicon precursor can includehexachlorodisilane (Si₂Cl₆, HCDS).

Suitable nitrogen precursors for a SiN sub-cycle can include a varietyof nitrogen-containing reactants. In some embodiments, a nitrogenprecursor can include a hydrogen bonded to a nitrogen (N—H). In someembodiments, a suitable nitrogen precursor can be ammonia (NH₃). In someembodiments, a suitable nitrogen precursor can be hydrazine (N₂H₄). Insome embodiments, a suitable nitrogen precursor can comprise one or morereactive species generated by a nitrogen-containing plasma. In someembodiments, a suitable nitrogen precursor can comprise one or morereactive species generated by a hydrogen-containing plasma. For example,a suitable nitrogen precursor can include nitrogen-containing radicals,hydrogen-containing radicals, nitrogen atoms, hydrogen atoms and/orcombinations thereof.

Suitable precursors comprising silicon and carbon for a SiCN sub-cyclecan include silylalkane. In some embodiments, a precursor comprisingsilicon and carbon can include bis(trichlorosilyl)methane (BTCSMe),1,2-bis(trichlorosilyl)ethane (BTCSEt), and/or a combination thereof. Insome embodiments, a precursor comprising silicon and carbon has a—Si—R—Si— group, where R can be C₁-C₈ hydrocarbon, such as C₁-C₃ alkylchain. In some embodiments, a precursor comprising silicon and carbon isa halogen substituted silylalkane, preferably the halogen is chloride.In some embodiments, a precursor comprising silicon and carbon has atleast two silicon atoms which are connected to each other through carbonand/or hydrocarbon. In some embodiments, a precursor comprising siliconand carbon is an unsubstituted silylalkane, such as bis(silyl)alkane,tris(silyl)alkane and/or tetrakis(silyl)alkane. In some embodiments, aprecursor comprising silicon and carbon is a substituted silylalkane,such as bis(halosilyl)alkane, tris(halosilyl)alkane and/ortetrakis(halosilyl)alkane. In some embodiments, a silyl group of thesilylalkane can be substituted with substituents other than halogens(e.g., substituted with an alkyl group).

Suitable nitrogen precursors for a SiCN sub-cycle can include a reactanthaving a hydrogen bonded to a nitrogen (N—H), such as ammonia (NH₃). Insome embodiments, a suitable nitrogen precursor can be hydrazine (N₂H₄).In some embodiments, a suitable nitrogen precursor can comprise one ormore reactive species generated by a nitrogen-containing plasma. In someembodiments, a suitable nitrogen precursor can comprise one or morereactive species generated by a hydrogen-containing plasma. For example,a suitable nitrogen precursor can include nitrogen-containing radicals,hydrogen-containing radicals, nitrogen atoms, hydrogen atoms and/orcombinations thereof. A SiCN sub-cycle nitrogen precursor may be thesame as or different a SiN sub-cycle nitrogen precursor. For example,both a nitrogen precursor for the SiCN sub-cycle and a nitrogenprecursor for the SiN sub-cycle may include ammonia.

In some embodiments, the substrate on which deposition is desired, suchas a semiconductor workpiece, is loaded into a reactor. The reactor maybe part of a cluster tool in which a variety of different processes inthe formation of an integrated circuit are carried out. In someembodiments, one or more deposition processes described herein can beperformed in a batch reactor, including for example in a mini-batchreactor (e.g., a reactor having a capacity of eight substrates or less)and/or a furnace batch reactor (e.g., a reactor having a capacitor offifty or more substrates). In some embodiments, one or more depositionprocesses described herein can be performed in a single wafer reactor.In some embodiments, a reactor having a cross-flow configuration can besuitable (e.g., a reactor chamber configured to provide gas flowparallel or substantially parallel to a substrate surface positioned inthe reactor chamber). In some embodiments, a reactor having a showerheadconfiguration can be suitable (e.g., a reactor configured to provide gasflow perpendicular or substantially perpendicular to a substrate surfacepositioned in the reactor).

Exemplary single wafer reactors are commercially available from ASMAmerica, Inc. (Phoenix, Ariz.) under the tradenames Pulsar® 2000 andPulsar® 3000 and ASM Japan K.K (Tokyo, Japan) under the tradename Eagle®XP and XP8. Exemplary batch ALD reactors are commercially available fromand ASM Europe B.V (Almere, Netherlands) under the tradenames A400™ andA412™.

A reaction chamber within which a SiCN deposition processes is performedmay be purged and/or evacuated between precursor pulses, for example toremove excess reactants and/or reaction byproducts from the reactionchamber. The flow rate and time of each precursor, is tunable, as is thepurge and/or evacuation step, allowing for control of the filmcomposition.

According to some embodiments of the present disclosure, the pressure ofthe reaction chamber during processing is maintained at about 0.01 Torrto about 50 Torr, preferably from about 0.1 Torr to about 10 Torr.

A thermal ALD process for a SiN deposition sub-cycle can include asilicon precursor comprising octachlorotrisilane (Si₃Cl₈, OCTS) and/orhexachlorodisilane (Si₂Cl₆, HCDS), and a nitrogen precursor comprisingammonia (NH₃). Exposing a substrate to the silicon precursor (e.g.,block 104 of FIG. 1) can include exposing the substrate to Si₃Cl₈ and/orSi₂Cl₆. For example, Si₃Cl₈ and/or Si₂Cl₆ can be fed into a reactionchamber (e.g., a silicon precursor pulse) for a duration of timesufficient to form up to a monolayer on the substrate surface. Exposingthe substrate to the nitrogen precursor in the SiN deposition sub-cycle(e.g., block 108 of FIG. 1) can include exposing the substrate to NH₃.For example, NH₃ can be fed into the reaction chamber (e.g., a nitrogenprecursor pulse) for a duration of time sufficient to react with theadsorbed silicon precursor.

A thermal ALD process for a SiCN deposition sub-cycle can include aprecursor comprising silicon and carbon, for example a precursorcomprising bis(trichlorosilyl)methane (BTCSMe) and/or1,2-bis(trichlorosilyl)ethane (BTCSEt), and a nitrogen precursorcomprising, for example, ammonia (NH₃). Exposing a substrate to theprecursor comprising the silicon and carbon (e.g., block 112 of FIG. 1)can include exposing the substrate to BTCSMe and/or BTCSEt. For example,BTCSMe and/or BTCSEt can be fed into a reaction chamber (e.g., a pulsefor introducing the precursor comprising the silicon and carbon) for aduration of time sufficient to form up to a monolayer on the substratesurface. Exposing the substrate to the nitrogen precursor of the SiCNdeposition sub-cycle (e.g., block 114 of FIG. 1) can include exposingthe substrate to NH₃. For example, NH₃ can be fed into a reactionchamber (e.g., a nitrogen precursor pulse) for a duration of timesufficient to react with the silicon and carbon precursor on thesubstrate surface.

The pulse length for a silicon precursor pulse (e.g., for a SiNsub-cycle) and/or a nitrogen precursor pulse (e.g., for a SiN sub-cycleand/or a SiCN sub-cycle) can be from about 0.05 seconds to about 5.0seconds, including about 0.1 seconds to about 3 seconds, and about 0.2seconds to about 1.0 second. In some embodiments, the pulse length for asilicon precursor can be different from that of a nitrogen precursor ofa SiN sub-cycle and/or a nitrogen precursor of a SiCN sub-cycle. In someembodiments, the pulse length for a silicon precursor can be similar toor the same as that of a nitrogen precursor. For example, a nitrogenprecursor pulse of a SiN sub-cycle and/or a SiCN sub-cycle, and/or asilicon precursor pulse can be about 1 second. In some embodiments, thepulse length for a precursor comprising silicon and carbon (e.g., for aSiCN sub-cycle) can be about 0.1 seconds to about 1 second, includingabout 0.2 seconds to about 0.5 seconds. For example, a pulse length fora precursor comprising silicon and carbon can be about 0.25 seconds.

In some embodiments, a precursor pulse for delivering one or moreprecursors into a reaction chamber in an ALD process can be followed bya removal process, such as for removal of excess precursors and/orreaction byproducts from the vicinity of the substrate surface. Theremoval process may include evacuating reaction byproducts and/or excessreactants between precursor pulses, for example by drawing a vacuum onthe reaction chamber to evacuate excess reactants and/or reactionbyproducts. In some embodiments, the removal process includes a purgeprocess. A gas such as nitrogen (N₂), argon (Ar) and/or helium (He) canbe used as a purge gas to aid in the removal of the excess reactantsand/or reaction byproducts.

In some embodiments, a purge pulse following a pulse of the siliconprecursor and/or a pulse of the nitrogen precursor (e.g., for a SiNsub-cycle and/or a SiCN sub-cycle) can have a pulse length of about 1second to about 20 seconds. For example, a purge pulse following asilicon precursor pulse and/or a nitrogen precursor pulse for a SiNsub-cycle and/or a nitrogen precursor pulse for a SiCN sub-cycle canhave a pulse length of about 5 seconds. In some embodiments, a purgepulse comprising nitrogen (N₂) gas for removing excess reactants and/orbyproducts from the reaction chamber after a silicon precursor pulse canhave a pulse length of about 5 seconds. In some embodiments, a purgepulse following a pulse of the precursor comprising silicon and carboncan have a pulse length of about 1 second to about 10 seconds. Forexample, a purge pulse comprising nitrogen (N₂) gas following a pulse ofthe precursor comprising silicon and carbon can have a pulse length ofabout 3 seconds. For example, a precursor pulse length for exposing asubstrate to a silicon precursor in a SiN sub-cycle can be about 1second, followed by a purge process of about 5 seconds. In someembodiments, a precursor pulse length for exposing the substrate to anitrogen precursor in a SiN deposition sub-cycle and/or a SiCNdeposition sub-cycle can be about 1 second. In some embodiments, thenitrogen precursor pulse in a SiN deposition sub-cycle and/or a SiCNdeposition sub-cycle can be followed by a purge process having aduration of about 5 seconds. In some embodiments, a precursor pulselength for exposing the substrate to a silicon precursor comprisingsilicon and carbon in a SiCN deposition sub-cycle can be about 0.25seconds. In some embodiments, the precursor comprising silicon andcarbon precursor pulse can be followed by a purge process of about 3seconds.

In some embodiments, a silicon carbon nitride (SiCN) film can be grownat about 450° C., for example in a Pulsar 3000® reactor on 300 mmsilicon wafers. The process for growing the silicon carbon nitride(SiCN) film can include SiN sub-cycles and SiCN sub-cycles (e.g.,thermal ALD processes). The silicon precursor can compriseoctachlorotrisilane (Si₃Cl₈, OCTS), the nitrogen precursor for both theSiN sub-cycle and the SiCN sub-cycle can comprise ammonia (NH₃), and theprecursor comprising silicon and carbon can comprisebis(trichlorosilyl)methane (BTCSMe) and/or 1,2-Bis(trichlorosilyl)ethane(BTCSEt). The pulse lengths for OCTS and/or NH₃ can be about 1.0 second(s), purge length following an OCTS and/or NH₃ pulse can be about 5seconds, the pulse length of BTCSMe and/or BTCSEt can be about 0.25 s,and purge length can be about 3 s after a BTCSMe and/or BTCSEt pulse.

In some embodiments, precursors, such as OCTS, BTCSMe and/or BTCSEt, canbe stored in one or more respective gas bubblers. For example, one ormore of the gas bubblers may be maintained at a temperature of about 40°C. Vapor phase precursors, such as OCTS, BTCSMe and/or BTCSEt may beprovided to the reactor from the gas bubblers. For example, a mass flowrate of the OCTS, BTCSMe and/or BTCSEt into the reactor may becontrolled by the extent to which a flow valve to the reactor is keptopen (e.g., extent to which a needle valve is kept open). In someembodiments, a nitrogen precursor can be provided to the reactor from agas source regulated at a pressure of about 1.5 bar. For example, themass flow rate of the nitrogen precursor may be determined by the extentto which a flow valve to the reactor is kept open (e.g., extent to whicha needle valve is kept open).

Graph 200 of FIG. 2 includes film growth rate curves which show examplesof dependence of growth rates on a SiCN sub-cycle percentage for siliconcarbon nitride (SiCN) films, for complete cycles and sub-cycles. In FIG.2, a film growth rate for each complete cycle or each sub-cycle of adeposition process, measured in angstroms per cycle ({acute over(Å)}/cycle), is graphed against a SiCN sub-cycle percentage of thecorresponding complete cycle used in forming the film. A complete cycleused in forming the films shown in FIG. 2 included a SiN sub-cycle inwhich the silicon precursor included octachlorotrisilane (OCTS) and thenitrogen precursor included ammonia. The film growth rate curves 202 and206 correspond to films deposited using a SiCN sub-cycle in which theprecursor comprising silicon and carbon included BTCSMe and the nitrogenprecursor included ammonia. The film growth rate curve 202 showsdependence of the film growth rate per SiCN sub-cycle, while film growthrate curve 206 shows dependence of the film growth rate per completecycle. The film growth rate curves 204 and 208 correspond to filmsdeposited using a SiCN sub-cycle in which the precursor comprisingsilicon and carbon included BTCSEt and the nitrogen precursor includedammonia. Film growth rate curve 204 shows dependence of the film growthper SiCN sub-cycle, while the film growth rate curve 208 showsdependence of the film growth rate per complete cycle.

The films of FIG. 2 can be formed according to one or more processesdescribed herein. For example, a film formed using a deposition processhaving a SiCN sub-cycle percentage of about 80% was deposited using anumber of complete cycles having one silicon nitride (SiN) depositionsub-cycle (e.g., one SiN sub-cycle) and four silicon carbon nitride(SiCN) deposition sub-cycles (e.g., four SiCN sub-cycles). A completecycle may include a SiN deposition sub-cycle in which pulsing of asilicon precursor (e.g., OCTS) is followed by a purge process and thenpulsing of a nitrogen precursor of the SiN deposition sub-cycle (e.g.,ammonia (NH₃)) followed by a purge process, the SiN sub-cycle beingfollowed by four SiCN sub-cycles in which each SiCN sub-cycle includedpulsing of a precursor comprising silicon and carbon (e.g., BTCSMe forcurves 202, 206, and BTCSEt for curves 204 and 208) followed by a purgeprocess and then pulsing of a nitrogen precursor of the SiCN sub-cycle(e.g., ammonia (NH₃)) followed by a purge process. The one or more SiNsub-cycles and/or SiCN sub-cycles can comprise an ALD process.

FIG. 2 shows that a growth rate per sub-cycle for each of the SiCNdeposition sub-cycles including the precursor comprising silicon andcarbon (e.g., an effective growth rate) generally decreases (e.g.,decreases linearly) with an increase in the fraction of SiCN sub-cyclesin the corresponding complete cycle, or with an increase in the SiCNsub-cycle percentage. FIG. 2 also shows that, advantageously, filmgrowth rate per complete cycle for each of the complete cycles increaseswith an increase in the fraction of SiCN sub-cycles in the correspondingcomplete cycle, or with an increase in the SiCN sub-cycle percentage.Without being limited by any particular theory or mode of operation,FIG. 2 may demonstrate that addition of a SiCN sub-cycle facilitatesfilm growth rate of a SiCN film. For example, FIG. 2 shows that withaddition of SiCN sub-cycles the film growth rate increased above thefilm growth rate for a process in which no SiCN sub-cycle was included(e.g., the film growth rate of SiCN films increased above 0.25 Å/cycle,the growth rate of the SiN film). Further without being limited bytheory, a deposition process including an ALD process with both SiNsub-cycles and SiCN sub-cycles may provide reactive surface groups tofacilitate SiCN film growth. For example, —SiCl₃ groups can be reactivetowards —NH and/or —NH₂ functional groups on a substrate surface, while−NH and/or —NH₂ functional groups may not be reactive towards —CH₂surface functional groups, such that no or substantially no reactivesurface groups are left for precursors to react after a few cycles ofthe SiCN sub-cycles, which includes the precursor comprising silicon andcarbon. The SiN sub-cycle may thereby facilitate providing reactivesurface functional groups for continued SiCN film growth.

FIG. 3 shows a table listing examples of film compositions provided byanalysis using X-ray photoelectron spectroscopy (XPS) of silicon carbonnitride (SiCN) films deposited on a substrate using processes asdescribed herein, each film having a thickness as listed in Table 3,expressed in nanometers, nm. A thickness of about 80 angstroms (Å) ofSiCN film was sputtered and/or removed from a surface of each of theSiCN films prior to the XPS analysis for determining film bulkcompositions. The table shown in FIG. 3 quantifies the amount of carbonatoms (C), nitrogen atoms (N), oxygen atoms (O), and silicon atoms (Si),expressed as an atomic percent, for each of the corresponding SiCNfilms. The film composition labeled with “SiCN-1” corresponds to a filmformed using a SiCN deposition sub-cycle in which the precursorcomprising silicon and carbon included BTCSMe. The film compositionlabeled with “SiCN-2” corresponds to a film formed using a SiCNdeposition sub-cycle in which the precursor comprising silicon andcarbon included BTCSEt. The table in FIG. 3 shows that carbon wasincorporated into the silicon nitride films. The table shows that theSiCN-1 film had a thickness of about 19 nm and contained about 5.2atomic % C while the SiCN-2 film had a thickness of about 26 nm andcontained about 9.9 atomic % C. Analysis of the SiCN-1 and the SiCN-2films indicated that at least a portion of the carbon atoms (C) in thefilms was bonded to a silicon atom (Si). For example, most of the C inthe SiCN-1 and the SiCN-2 films was bonded to a Si atom, such as about80% of the C in the SiCN-1 and the SiCN-2 films were bonded to a Siatom. In some embodiments, all or substantially all of the C in a SiCNfilm is bonded to a Si atom. In some embodiments, about 50% to about100% of the C atoms are bonded to a Si atom, and in some embodimentsabout 70% to about 90% of the C atoms are bonded to a Si atom.

In some embodiments, a SiCN film can have a C content of about 1 atomic% to about 30 atomic %, preferably about 2 atomic % to about 20 atomic%. For example, a SiCN film can have a C content of about 5 atomic % toabout 15 atomic %.

Analysis of the SiCN-1 and the SiCN-2 films also indicated that thefilms contained a significant quantity of oxygen atoms (O). For example,concentration of O in the SiCN-1 and/or SiCN-2 film increased towards asurface of the film. Without being limited by theory, the O content ofthe films may be due, at least in part, to post-deposition oxidation ofthe films.

The SiCN films listed in the table of FIG. 3 can be deposited using oneor more processes as described herein, including for example one or moreprocess described with reference to FIG. 2. For example, each of thelisted SiCN films was formed using a deposition process including anumber of complete cycles, each complete cycle including one siliconnitride (SiN) deposition sub-cycle and four SiCN deposition sub-cycles(e.g., the complete cycle having a SiCN sub-cycle percentage of 80%).The SiN deposition sub-cycle for both the SiCN-1 film and the SiCN-2film included a silicon precursor comprising OCTS and a nitrogenprecursor comprising ammonia. The SiCN deposition sub-cycles for boththe SiCN-1 film and the SiCN-2 film included a nitrogen precursorcomprising ammonia. The SiCN-1 film was deposited using about 500complete cycles. The SiCN-2 film was deposited using about 750 completecycles.

As shown in FIG. 3, one or more deposition process parameters can beselected to control a carbon (C) content of a silicon carbon nitride(SiCN) film. For example, a C content of a SiCN film may depend on theselected precursor comprising silicon and carbon and/or the number ofcomplete deposition cycles used in forming the film. In someembodiments, a process parameter for controlling a C content of the SiCNfilm can include, for example, a number of SiCN deposition sub-cyclesfor each complete cycle of the deposition process, and/or a pulseduration of the precursor pulse for the precursor comprising silicon andcarbon).

In some embodiments, a SiCN film deposited on a substrate candemonstrate a film non-uniformity (e.g., a 1-sigma non-uniformity) ofabout 5% to about 10%.

FIG. 4 shows examples of wet etch rate performances, in aqueoushydrofluoric (HF) acid solution (e.g., aqueous HF solution have aconcentration of about 0.5 weight %, or dHF), of a silicon nitride (SiN)film and silicon carbon nitride (SiCN) films formed using depositionprocesses having SiCN sub-cycle percentages of about 50%, about 80% andabout 90%. The etch rate performance is expressed in nanometers perminute (nm/min). The SiN film was formed using a number of depositioncycles in which the substrate was alternately and sequentially contactedwith a silicon precursor comprising OCTS and a nitrogen precursorcomprising ammonia (NH₃). The SiCN films can be formed using one or moredeposition processes as described herein, including for example one ormore deposition processes as described with reference to FIG. 2. Forexample, the SiCN film deposition process included a number of completecycles, where each complete cycle included a SiN sub-cycle and a numberof SiCN sub-cycles, such that each complete cycle had the desired SiCNsub-cycle percentage (e.g., about 50%, about 80% and about 90%). FIG. 4shows examples of etch rate performances of SiCN films deposited usingSiCN sub-cycles having BTCSMe as the precursor comprising silicon andcarbon, and ammonia as the nitrogen precursor.

FIG. 4, shows that addition of carbon into a silicon nitride film canfacilitate reduction in a wet etch rate of the film. The silicon carbonnitride (SiCN) films demonstrated a lower wet etch rate than the siliconnitride film. For example, the silicon nitride (SiN) film demonstratedan etch rate of about 90 nanometers per minute (nm/min) in the aqueousHF solution, while the SiCN film deposited using a process having a SiCNsub-cycle percentage of about 90% demonstrated an etch rate of about 19nm/min. A significant reduction in etch rate, for example as compared toa SiN film, can also be observed in the SiCN film deposited using aprocess having a SiCN sub-cycle percentage of about 50%. For example,the SiCN film deposited using a process having a SiCN sub-cyclepercentage of about 50% demonstrated an etch rate of about 35 nm/min, ascompared to an etch rate of about 90 nm/min demonstrated by the SiNfilm.

Additionally, as shown in FIG. 4, wet etch rate in the aqueous HFsolution of the SiCN films deposited using BTCSMe decreased as the SiCNsub-cycle percentages increased. For example, the SiCN film depositedwith the SiCN sub-cycle percentage of about 50% demonstrated a wet etchrate of about 35 nm/min, while the SiCN film deposited with the SiCNsub-cycle percentage of about 90% demonstrated a wet etch rate of about19 nm/min.

In some embodiments, a SiCN film deposited using a SiCN sub-cycle whichincludes BTCSEt as the precursor comprising silicon and carbon candemonstrate etch rates in dilute aqueous HF acid solution (e.g., aqueousHF acid solution having a concentration of about 0.5 weight %) similarto that of SiCN films deposited using BTCSMe as the precursor comprisingsilicon and carbon. For example, an etch rate of a SiCN film depositedusing a deposition process having a SiCN sub-cycle percentage of about80% and BTCSEt as the precursor comprising silicon and carbon can havean etch rate in dilute aqueous HF acid solution of about 21nanometers/min (nm/min), demonstrating significant reduction in etchrate as compared to a SiN film.

In some embodiments, a silicon nitride (SiN) film can have an etch ratein a dilute aqueous hydrofluoric acid solution (e.g., a concentration ofabout 0.5 weight %, or dHF) of about 80 nanometers per minute (nm/min)to about 100 nm/min. In some embodiments, a silicon carbon nitride(SiCN) film formed by a deposition process having a SiCN sub-cyclepercentage of about 50% can have an etch rate in dHF of about 30 nm/minto about 40 nm/min. In some embodiments, a SiCN film formed by adeposition process having a SiCN sub-cycle percentage of about 80% canhave an etch rate in dHF of about 18 nm/min to about 25 nm/min. In someembodiments, a SiCN film formed by a deposition process having a SiCNsub-cycle percentage of about 90% can have an etch rate in dHF of about17 nm/min to about 21 nm/min.

Plasma Treatment Process

As described herein, a silicon carbon nitride (SiCN) deposition process(e.g., a thermal ALD process as described herein) can be combined with aplasma treatment process. For example, the plasma treatment process canbe applied to a SiCN film deposited using thermal ALD depositionprocesses. The combination of the SiCN deposition process and the postfilm deposition plasma treatment process can facilitate formation of aSiCN film having desirable characteristics, including for example, SiCNfilms having desired wet etch rate, wet etch selectivity relative tothermally formed silicon oxide (TOX) while maintaining desired conformalfilm deposition on three-dimensional structures having high aspectratios (e.g., aspect ratios of about 6 or higher). SiCN films havingsuch desirable characteristics may be particularly suitable for spacerapplications in semiconductor device fabrication.

In some embodiments, a wet etch rate (WER), in dHF, of a SiCN filmtreated by a plasma treatment process can be less than about 50% thanthat of thermal oxide film (e.g., thermally grown silicon oxide, TOX),including about 20% to about 30% that of TOX in dHF. For example, wetetch rates, in dHF, of SiCN films treated by a plasma treatment processcan be less than about 5 nanometers per minute (nm/min), preferably lessthan about 4 nm/min, more preferably less than about 2 nm/min, and mostpreferably less than about 1 nm/min.

In some embodiments, a SiCN film treated by a plasma treatment processcan be formed on a three-dimensional structure having sidewall and topregions (e.g., trench structures) such that a ratio of a wet etch rate,in dHF, of the SiCN film on a sidewall to a wet etch rate of the SiCNfilm on a top region is less than about 4, including less than about 3.In some embodiments, the ratio of the wet etch rate of the SiCN film onthe sidewall to that of the SiCN film on the top region in dHF can beabout 1.

FIG. 5 shows a flow chart of an example of a process 120 for forming asilicon carbon nitride film (e.g., a SiCN film), which includes theprocess 100 described with reference to FIG. 1 in combination with aplasma treatment process 116. For example, the process 100 (e.g., athermal ALD process) can be followed by the plasma treatment process 116so as to provide a SiCN film having desirable characteristics. In someembodiments, the number of times the plasma treatment process 116 isrepeated can be selected to provide the SiCN film having desirablecharacteristics. For example, a number of repetitions of the process 100can be followed by a number of repetitions of the plasma treatmentprocess 116. In some embodiments, a film formation process can includerepetitions of a process comprising a number of cycles of the process100 followed by a number of cycles of the plasma treatment process 116(e.g., a process including two repetitions can include a number ofcycles of the process 100, followed by a number of cycles of the plasmatreatment 116, followed by a number of cycles of the process 100, andfollowed by a number of cycles of the plasma treatment process 116).

A silicon carbon nitride film formed according to process 120 may not bea nanolaminate film. For example, separate and distinct layers may notbe visible within the silicon nitride film such that a continuous orsubstantially continuous film without or substantially without any filminterface layer within the film can be formed.

In some embodiments, a plasma treatment reactor could be a part of amulti-reactor processing system, such as a cluster tool. For example,the plasma treatment reactor may be a part of the same cluster tool as areactor used for depositing the SiCN film. For example, a batch reactorused for thermal ALD deposition of the SiCN film may be a part of thesame cluster tool as the reactor used for the plasma treatment processsuch that a substrate having the SiCN film deposited thereon can betransferred to the plasma treatment reactor without or substantiallywithout being exposed to ambient air, facilitating increased throughput.In some other embodiments, the plasma treatment reactor may be astand-alone reactor and it not part of a multi-reactor processingsystem.

Plasma treatments can be performed in a variety of processingenvironments, including for example in a showerhead PEALD reactor. Insome embodiments, one or more plasma treatment processes describedherein can be performed in a 300 mm showerhead plasma enhanced atomiclayer deposition (PEALD) reactor (e.g., GENI MP-3000MD RC2, commerciallyavailable from ASM Genitech Korea Ltd. of Cheonan-si, Korea). In someembodiments, the plasma treatment can be performed at a susceptortemperature of about 350° C. to about 450° C. For example, the plasmatreatment can be performed at a susceptor temperature of about 400° C.

In some embodiments, the plasma treatment can be performed at a pressureof about 1 Torr to about 3 Torr. For example, the plasma treatment canbe performed at a pressure of about 2 Torr (e.g., the plasma treatmentcan be performed while the reactor chamber is maintained at a pressureof about 2 Torr).

In some embodiments, the plasma treatment process can include a directplasma, and/or a remote plasma. A plasma for the plasma treatment may begenerated by applying RF power of from about 10 Watts (W) to about 2000W, preferably from about 50 W to about 1000 W, more preferably fromabout 100 W to about 500 W. In some embodiments, the RF power densitymay be from about 0.02 Watts per square centimeter (W/cm²) to about 2.0W/cm², preferably from about 0.05 W/cm² to about 1.5 W/cm². The RF powermay be applied to one or more plasma treatment process reactant gasesprovided to the reactor and/or to a remote plasma generator. Thus insome embodiments the plasma is generated in situ, while in otherembodiments the plasma is generated remotely.

A plasma treatment process can include a number of cycles, where one ormore cycles can include a sequence in which the plasma is powered on fora first duration of time and a second duration of time in which theplasma is turned off. For example, each cycle of the plasma treatmentcan include a first duration of time in which the plasma is turned on,follow by a second duration of time in which plasma is turned off.

In some embodiments, one or more plasma treatment process reactant gasescontinue to be supplied to the reactor chamber during the duration oftime in which the plasma is turned off. For example, one or more plasmatreatment process reactant gases can be continuously supplied to thereactor chamber during the treatment process, both during the time inwhich the plasma is turned on and during the time in which the plasma isturned off. In some embodiments, the plasma for the plasma treatmentprocess can be generated in the one or more reactant gases being flowedthrough the reactor chamber. For example, the flow of the one or morereactant gases can be continued while the plasma power is turned on togenerate the plasma in the reactant gases, and flow of one or more ofthe reactant gases can be continued also during the interval in whichthe plasma power is turned off. In some embodiments, not all reactantgases flowed through the reactor chamber for generating the plasma whenthe plasma power is on is flowed through the reactor chamber during theinterval (e.g., when the plasma power is off).

The plasma treatment process can include a number of cycles such that adeposited film can be exposed to the plasma for a duration of time toprovide a film having desired characteristics. The duration of time adeposited film is exposed to the plasma treatment can depend on a numberof parameters, including parameters relating to the deposited film(e.g., a film thickness of the deposited film having the desiredcharacteristics, such as increased resistance to wet etchant dHF),and/or parameters relating to a three-dimensional (3-D) structure uponwhich the film is deposited (e.g., a shape, dimension, and/or aspectratio of the 3-D structure).

In some embodiments, the plasma treatment can have a duration of atleast about 30 seconds (s), preferably at least about 1 minute (min),and more preferably at least about 2 min. For example, subjecting adeposited film to a total 10 minute plasma treatment can be performedusing 10 cycles in which each cycle includes 60 seconds during which theplasma is turned on followed by 30 seconds during which plasma is turnedoff (e.g., a sequence including 10×(60 seconds plasma on+30 secondsplasma off)). Including a period of time in one or more cycles of theplasma treatment in which the plasma is off may facilitate reduction inthe overheating of the plasma power source.

In some embodiments, a plasma treatment process can follow one or morecomplete cycles of a process for depositing a silicon carbon nitride(SiCN) film (e.g., a complete cycle including a SiN deposition sub-cycleand a number of SiCN deposition sub-cycles). For example, a process forforming a plasma treated SiCN film can include repetition of thefollowing process: a number of complete cycles of a process fordepositing the SiCN film followed by a number of cycles of the plasmatreatment process. In some embodiments, a plasma treatment process canfollow a number of SiCN deposition sub-cycles and/or a SiN depositionsub-cycle. For example, one or more plasma treatment processes may beperformed after one or more SiN deposition sub-cycles, and/or one ormore SiCN deposition sub-cycles. In some embodiments, one or more plasmatreatment processes can be performed after each SiN deposition sub-cycleand/or each SiCN deposition sub-cycle. In some embodiments, a processfor providing a plasma treated SiCN film can include repetition of thefollowing process: one or more SiCN deposition sub-cycles followed byone or more cycles of the plasma treatment. In some embodiments, aprocess for providing a plasma treated SiCN film can include repetitionof the following process: a SiN deposition sub-cycle, followed byrepetition of a process including one or more SiCN deposition sub-cyclesfollowed by one or more cycles of the plasma treatment. In someembodiments, a process for providing a plasma treated SiCN film caninclude repetition of the following process: one or more SiN depositionsub-cycles followed by one or more cycles of the plasma treatment,followed by one or more SiCN deposition sub-cycles.

In some embodiments, suitable reactant gas for a plasma treatmentprocess can include nitrogen gas (N₂), hydrogen gas (H₂) and/or argon(Ar). Various reactant flow rates can be suitable. In some embodiments,flow rate of reactant gases can be selected so as to maintain a desiredreactor chamber pressure during the plasma treatment process (e.g., oneor more reactant gases having a flow rate to maintain a reactor chamberpressure of about 2 Torr). A flow rate for each of N₂, H₂ and/or Ar canbe about 20 standard cubic centimeters per minute (sccm) to about 2000sccm, preferably from about 50 sccm to 1000 sccm. In some embodiments,the flow rate of each of N₂ and/or H₂ can be about 20 sccm to about 1000sccm. For example, a flow rate for each of N₂, and/or H₂ can be about 50sccm. For example, a flow rate for Ar can be about 600 sccm.

The duration in which plasma is turned on in a cycle of a plasmatreatment process may or may not be the same as the duration in whichplasma is turned on in one or more other cycles of the plasma treatmentprocess. Other process parameters of a cycle in a plasma treatmentprocess, including for example, susceptor temperature, reactor chamberpressure, and/or reactant gas flow rate, may or may not be the same asthat of one or more other cycles of the plasma treatment process. Insome embodiments, the plasma treatment process can include a number ofrepetitions of cycles in which each cycle includes the same orsubstantially the same process parameters as other cycles of the plasmatreatment process.

In some embodiments, reactant gases are purified prior to beingintroduced into the reactor. Purification of reactant gases can beperformed using a variety of suitable commercially available inert gaspurifier (e.g., Gatekeeper® Gas Purifier available from Entegris, Inc.of Billerica, Mass.).

In some embodiments, the reaction chamber in which plasma treatmentprocess is performed can undergo a cleaning procedure prior toinitiating the plasma treatment process, such as prior to beginning afirst cycle of the plasma treatment process. In some embodiments, thecleaning procedure can be performed between two cycles of the plasmatreatment process. A reaction chamber cleaning procedure can includeapplying a plasma power of about 500 Watts (W) to about 700 W, such asabout 600 W and supplying a reaction chamber clean reactant gas (e.g.,argon (Ar)) for a suitable duration of time. Various durations can besuitable for the cleaning procedure, including for example from about 1minute to about 5 minutes. In some embodiments, the cleaning procedurecan be performed for about 2 minutes. For example, a reaction chamberclean procedure can include providing an Ar gas flow into the reactionchamber, with a plasma power of about 600 Watts (W), for a duration ofabout 2 minutes. In some embodiments, a flow rate for Ar in the chamberclean process can be about 600 sccm. Other Ar flow rates may also besuitable.

As described herein, application of a plasma treatment process asdescribed herein to a silicon nitride based film may facilitatereduction in the wet etch rate of the film. FIG. 6 shows a graph 500 offilm thickness curves showing changes in film thicknesses, expressed innanometers (nm), of silicon nitride (SiN) films exposed to a wet etchant(e.g., aqueous hydrofluoric acid solution having a concentration ofabout 0.5 weight %, or dHF) as a function of the duration of exposure tothe wet etchant, expressed in seconds (s). Film thickness curve 502graphs the change in thickness of a SiN film which has not undergone apost film deposition plasma treatment process. Film thickness curves504, 506, 508 and 510 graph changes in thicknesses of SiN films whichhad undergone post deposition plasma treatment processes. Film thicknesscurve 504 graphs the change in thickness of a SiN film which hadundergone a plasma treatment process comprising reactant gases nitrogengas (N₂), hydrogen gas (H₂), and argon (Ar). Film thickness curve 506graphs the change in thickness of a SiN film which had undergone aplasma treatment process comprising reactant gases N₂ and Ar. Filmthickness curve 508 graphs the change in thickness of a SiN film whichhad undergone a plasma treatment process comprising reactant gas Ar, andfilm thickness curve 510 graphs the change in thickness of a SiN filmwhich had undergone a plasma treatment process comprising reactant gasesH₂ and Ar. The plasma treatment processes were performed using a plasmapower of about 200 Watts (W), at a reaction chamber pressure of about 2Torr and a susceptor temperature of about 400° C., and each treatmentproviding a number of cycles to expose the SiN films to plasma for atotal duration of about 10 minutes. Each cycle of the plasma treatmentprocess included about 60 seconds during which the plasma power was kepton followed by 30 seconds during which plasma power was turned off. Thecycle was repeated 10 times such that the SiN films were exposed toplasma for the total of about 10 minutes. The flow rates of N₂ and H₂were about 50 standard cubic centimeters per minute (sccm). The flowrate of Ar can be selected, for example, to achieve a desired reactionchamber pressure during the plasma treatment process. In someembodiments, a flow rate for Ar can be about 600 sccm.

FIG. 6 shows improved etch resistance of the SiN film against diluteaqueous hydrofluoric acid solution (e.g., dHF) with application of apost SiN film deposition plasma treatment. As compared to the SiN filmwhich did not undergo plasma treatment subsequent to the filmdeposition, each of the SiN films which had undergone subsequent plasmatreatment, films corresponding to film thickness curves 504, 506, 508and 510, showed reduced rate of decrease in film thickness when exposedto dHF. Referring to FIG. 6, of the graphed examples of plasma treatmentprocesses, film thickness curve 510 shows that the SiN film whichunderwent a plasma treatment process using reactant gases H₂ and Ardemonstrated the most resistance against etching by dHF. For example, alinear fit of the graphed data points of film thickness curve 510 showsa wet etch rate of about 2.9 nanometers per minute (nm/min) for the SiNfilm which was subjected to the plasma treatment process includingreactant gases hydrogen (H₂) and argon (Ar), demonstrating an etch ratecomparable to that of thermally formed silicon oxide (TOX) in dHF (e.g.,TOX can have an etch rate in dHF of about 2.0 nm/min to about 2.5nm/min).

FIG. 7 is a graph 600 film thickness curves showing changes in filmthicknesses, expressed in nanometers (nm), of silicon carbon nitride(SiCN) films, as a function of duration of exposure to a wet etchant(e.g., aqueous hydrofluoric acid solution having a concentration ofabout 0.5 weight %, or dHF), expressed in seconds (s). Film thicknesscurve 602 graphs the change in thickness of a SiCN film which has notundergone a post SiCN film deposition plasma treatment process. Filmthickness curve 604 graphs the change in thickness of a SiCN film whichhas undergone a post SiCN film deposition plasma treatment processcomprising reactant gases nitrogen (N₂), hydrogen (H₂), and argon (Ar).Film thickness curve 606 graphs the change in thickness of a SiCN filmwhich has undergone a post SiCN film deposition plasma treatment processcomprising reactant gases N₂ and Ar. Film thickness curve 608 graphs thechange in thickness of a SiCN film which has undergone a post SiCN filmdeposition plasma treatment process comprising reactant gas Ar, and filmthickness curve 610 graphs the change in thickness of a SiCN film whichhas undergone a post SiCN film deposition plasma treatment processcomprising reactant gases H₂ and Ar.

The SiCN films were formed according to one or more processes describedwith reference to FIG. 2. For example, the SiCN films of FIG. 7 wereformed using a deposition process which includes a SiCN sub-cyclepercentage of about 80% and BTCSMe as the precursor comprising siliconand carbon. The plasma treatment processes can include the variousprocess parameters as described herein. For example, the plasmatreatment processes were performed using a plasma power of about 200Watts (W), at a reactor chamber pressure of about 2 Torr and a susceptortemperature of about 400° C., and each treatment providing a number ofcycles to expose the SiCN films to plasma for a total duration of about10 minutes (e.g., 10 cycles, where each cycle included 60 seconds ofplasma power on followed by 30 seconds of plasma power off). The plasmatreatment process was performed after performing a number of completecycles for depositing the SiCN film. The flow rates of N₂ and H₂ wereabout 50 standard cubic centimeters per minute (sccm). In someembodiments, a flow rate for Ar can be about 600 sccm. In someembodiments, the flow rate of Ar can be selected, for example, toachieve a desired reactor chamber pressure during the plasma treatmentprocess.

FIG. 7 shows that of the graphed silicon carbon nitride (SiCN) films,the etch resistance of the SiCN film treated with a plasma treatmentprocess using reactant gases hydrogen (H₂) and argon (Ar) demonstratedsignificant improvement. For example, a linear fit of the graphed datapoints of film thickness curve 610 shows that the SiCN film subjected toa plasma treatment process using H₂ and Ar demonstrated an etch rate ofabout 0.6 nanometers per minute (nm/min), an even lower etch rate in dHFthan the SiN film treated with the plasma treatment process using H₂ andAr described herein with reference to FIG. 6 (e.g., the SiN filmcorresponding to film thickness curve 510 as described herein withreference to FIG. 6).

FIG. 8 is a graph 700 of film thickness curves showing changes in filmthicknesses, expressed in nanometers (nm), of silicon nitride (SiN)films and silicon carbon nitride (SiCN) films, as a function of durationof exposure to a wet etchant (e.g., aqueous hydrofluoric acid solutionhaving a concentration of about 0.5 weight %, or dHF), expressed inseconds (s). Film thickness curve 702 graphs the change in thickness ofa SiN film was had not undergone a plasma treatment subsequent to SiNfilm deposition. Film thickness curve 704 graphs the change in thicknessof a SiN film which had undergone a plasma treatment process comprisingreactant gases nitrogen hydrogen (H₂) and argon (Ar). Film thicknesscurve 706 graphs the change in thickness of a SiCN film which had notundergone a post film deposition plasma treatment process, while filmthickness curve 708 graphs the change in thickness of a SiCN film whichhad undergone a plasma treatment process comprising reactant gases H₂and Ar. The SiCN films can be formed according to one or more processesdescribed herein. For example, the SiCN films were formed using adeposition process described with reference to FIG. 2, using a SiCNsub-cycle percentage of about 80% and BTCSEt as the precursor comprisingsilicon and carbon. The plasma treatment processes can include thevarious process parameters as described herein. For example, the plasmatreatment processes can be performed using a plasma power of about 200Watts (W), at a reactor chamber pressure of about 2 Torr and a susceptortemperature of about 400° C., and each treatment providing a number ofcycles to expose the SiCN films to plasma for a total duration of about30 minutes. For example, a plasma treatment process comprising 30 cycleswas performed, where each cycle included 60 seconds of plasma onfollowed by 30 seconds of plasma off. The plasma treatment process canbe performed after performing a number of complete cycles for depositinga SiCN film. The flow rate of H₂ was about 50 standard cubic centimetersper minute (sccm). The flow rate of Ar was about 600 sccm.

FIG. 8 shows that the silicon nitride (SiN) film and silicon carbonnitride (SiCN) film can demonstrate significantly increased resistanceto the wet etchant (e.g., dHF) after undergoing plasma treatmentprocesses comprising reactant gases hydrogen (H₂) and argon (Ar), forexample as compared to a SiN film and/or a SiCN film which was notsubjected to a post film deposition plasma treatment process. Filmthickness curve 702 shows that a SiN film not treated by a plasmatreatment process can be completely or substantially completely removedafter being exposed to the dHF for about 15 seconds. Meanwhile, filmthickness curve 704 shows that a SiN film which underwent a plasmatreatment process can demonstrate a significantly reduced etch rate whenexposed to dHF for at least about 2 minutes before etch rate of the SiNfilm increases. FIG. 8 shows that the SiN film of film thickness curve704 was not completely or substantially completely etched until beingexposed to dHF for at least about 240 seconds. FIG. 8 additionally showsthat the SiCN film corresponding to film thickness curve 708, which wastreated with a plasma treatment process using reactant gases comprisingH₂ and Ar, can be resistant or substantially resistant to removal by dHFduring the exposure to the dHF etchant for at least about 6 minutes.

FIG. 9 shows a graph 800 of film thickness curves showing changes infilm thicknesses, expressed in nanometers (nm), of silicon carbonnitride (SiCN) films deposited using various SiCN deposition sub-cyclepercentages, as a function of duration of exposure to a wet etchant(e.g., aqueous hydrofluoric acid solution having a concentration ofabout 0.5 weight %, or dHF), expressed in seconds (s). FIG. 9 alsoincludes a film thickness curve for a SiN film. The films of FIG. 9 wereexposed to a plasma treatment processes including reactant gaseshydrogen (H₂) and argon (Ar). Film thickness curve 802 graphs the changein thickness of the SiN film. Film thickness curve 804 graphs the changein thickness of a SiCN film formed using a deposition process having aSiCN sub-cycle percentage of about 50%. Film thickness curve 806 graphsthe change in thickness of a SiCN film formed using a deposition processhaving a SiCN sub-cycle percentage of about 70%. Film thickness curve808 graphs the change in thickness of a SiCN film formed using adeposition process having a SiCN sub-cycle percentage of about 80%. TheSiCN film can be formed according to one or more processes describedherein, such as the deposition process described with reference to FIG.2. For example, the SiCN films were formed using BTCSEt as the precursorcomprising silicon and carbon. The plasma treatment processes caninclude the various process parameters as described herein. For example,the plasma treatment processes were performed using a plasma power ofabout 200 Watts (W), at a reactor chamber pressure of about 2 Torr and asusceptor temperature of about 400° C., and each treatment providing anumber of cycles to expose the SiCN films to plasma for a total durationof about 30 minutes (e.g., 30 cycles, where each cycle included 60seconds of plasma on followed by 30 seconds of plasma off). In someembodiments, a plasma treated SiCN film can include performing theplasma treatment process after performing a number of complete cyclesfor depositing a SiCN film. The flow rate of H₂ was about 50 standardcubic centimeters per minute (sccm). The flow rate of Ar was about 600sccm.

The graph of FIG. 9 shows that a resistance against removal by the wetetchant (e.g., dHF) generally increases with increasing SiCN sub-cyclepercentage used in the deposition process of the SiCN film. Withoutbeing limited by theory, an increase in carbon content of the SiCN film,such as through use of increased SiCN deposition sub-cycle percentage inthe SiCN film deposition process, may facilitate increased resistanceagainst removal by dHF.

In some embodiments, a SiCN film formed according to one or moreprocesses as described herein can demonstrate a “skinning effect,” inwhich a first portion of the SiCN film provides increased resistance tothe wet etchant (e.g., dHF), and after the breaching of this firstportion of the SiCN film, resistance to the wet etchant decreasessignificantly and the wet etch rate increases (e.g., a wet etch rate ofthe SiCN film corresponding to film thickness curve 804 of FIG. 9 showsincreased etch rate in the dHF after being exposed to the dHF for about190 seconds, for example at which point the first portion of the SiCNfilm having increased resistance to dHF is breached).

In some embodiments, a process for forming a SiCN film layer for aspacer application can include one or more complete cycles of one ormore suitable deposition processes as described herein and/or a one ormore number of cycles of one or more suitable plasma treatment processesas described herein, so as to provide a desired thickness of the firstportion of the film having the increased resistance to the wet etchant.For example, a process for forming a SiCN film layer for a spacerapplication can include more than one complete cycles of one or moresuitable deposition processes and more than one cycle of one or moresuitable plasma treatment processes. For example, a 10 nanometers (nm)thick SiCN film which demonstrates desired resistance to the wet etchantcan be formed by repeating three times a process which can provide abouta 3 nm thick film having the desired wet etchant resistance (e.g., foruse in various semiconductor device applications, including in spacerapplications). In some embodiments, the post deposition plasma treatmentcycles can be repeated to achieve a desired thickness in the depositedfilm which can exhibit the desired resistance to wet etch.

FIG. 10A shows a field emission scanning electron microscopy (FESEM)image of a cross-section of an example of trench structures 900 having asilicon nitride (SiN) film 902 deposited upon the trench structures 900,and the SiN film 902 deposited on adjacent open area 904. The SiN film902 had undergone post film deposition plasma treatment, the plasmatreatment using reactant gases comprising hydrogen (H₂) and argon (Ar).The plasma treatment process can have one or more of the processparameters as described herein. For example, the plasma treatmentprocesses included a duration of about 30 minutes in which plasma wasturned on, performed using a plasma power of about 200 Watts (W), at areactor chamber pressure of about 2 Torr and a susceptor temperature ofabout 400° C., with the flow rate of H₂ at about 50 standard cubiccentimeters per minute (sccm) and the flow rate of Ar selected, forexample, to achieve the reactor chamber pressure of about 2 Torr duringthe plasma treatment process (e.g., at about 600 sccm).

FIG. 10B shows a field emission scanning electron microscopy (FESEM)image of a cross-section of the trench structures 900 having thedeposited silicon nitride (SiN) film 902, after the SiN film was exposedto a wet etchant (e.g., aqueous hydrofluoric acid having a concentrationof about 0.5 weight %, or dHF) for about 2 minutes. FIG. 10B shows thatwhile the SiN film 902 demonstrated desired conformality to theunderlying trench structures 900 both before and after being exposed todHF, portions of the SiN film 902 were removed after exposure to dHF.Portions of the SiN film 902 were removed from vertical sidewalls of thetrench structures 900, while the SiN film 902 remained or substantiallyremained on top surfaces between individual trenches of the trenchstructure 900, and the adjacent open area 904. Such a performance afterbeing exposed to dHF can be similar to that of a SiN film depositedusing a plasma enhanced atomic layer deposition (PEALD) process.

FIG. 11A shows a field emission scanning electron microscopy (FESEM)image of a cross-section of an example of a trench structures 1000having a silicon carbon nitride (SiCN) film 1002 deposited upon trenchstructures 1000, and the SiCN film 1002 deposited on adjacent open area1004. The SiCN film 1002 had undergone post film deposition plasmatreatment, the plasma treatment using reactant gases comprising hydrogen(H₂) and argon (Ar). As shown in FIG. 11A, the SiCN film 1002 comprisesa continuous or substantially continuous film in which distinct andseparate layers are not visible.

The plasma treatment process can have one or more of the processparameters as described herein. For example, the plasma treatmentprocesses had a duration of about 30 minutes in which plasma was turnedon, was performed using a plasma power of about 200 Watts (W), at areactor chamber pressure of about 2 Torr and a susceptor temperature ofabout 400° C., with the flow rate of H₂ at about 50 standard cubiccentimeters per minute (sccm) and the flow rate of Ar selected, forexample, to achieve the reactor chamber pressure of about 2 Torr duringthe plasma treatment process (e.g., at about 600 sccm). The SiCN filmcan be formed according to one or more processes as described herein,for example using a deposition process having a SiCN sub-cyclepercentage of about 80% and BTCSEt as the precursor comprising siliconand carbon. The plasma treatment process (e.g., a number of cycles ofthe treatment process) for providing the plasma treated SiCN film 1002was performed after performing a number of complete cycles fordepositing a SiCN film.

FIG. 11B shows a field emission scanning electron microscopy (FESEM)image of a cross-section of the trench structures 1000 having thesilicon carbon nitride (SiCN) film 1002 deposited upon the trenchstructures 1000 and the adjacent open area 1004, after the SiCN film1002 was exposed to a wet etchant (e.g., aqueous hydrofluoric acidhaving a concentration of about 0.5 weight %, or dHF) for about 2minutes. FIG. 11B shows that the SiCN film 1002 demonstrated desiredconformality to the underlying trench structures 1000 both before andafter being exposed to dHF. After exposure to dHF, the SiCN film 1002desirably remained or substantially remained on all surfaces of thetrench structures 1000, including vertical sidewalls of individualtrenches. FIG. 11B shows that a plasma treated SiCN film deposited on athree-dimensional (3-D) structure (e.g., trench structures) can beeffective in resisting removal from surfaces of the 3-D structure whenexposed to dHF for at least a duration of about 2 minutes, includingSiCN film on surfaces both between and within the 3-D structures, suchas SiCN film on sidewalls within the trench structures.

Measurements of film thickness taken of the SiCN film 1002 on surfacesof the trench structures 1000 before and after being exposed to the dHFdemonstrated that the SiCN film 1002 had an etch rate of less than about1 nanometers per minute (nm/min). As described herein, thermally formedoxide (TOX) can have a wet etch rate in dHF of about 2.0 nm/min to 2.5nm/min. The SiCN film 1002 desirably demonstrated an etch rate ratiorelative to the etch rate of TOX of less than about 0.5. A SiCN filmdemonstrating such a reduced etch rate in wet etchant, such as dHF, canadvantageously facilitate use of silicon nitride based materials inspacer applications.

FIG. 12 shows a field emission scanning electron microscopy (FESEM)image of a cross-section of an example of a trench structures 1100having a silicon carbon nitride (SiCN) film 1102 deposited upon thetrench structures 1100, after the SiCN film 1102 was exposed to a wetetchant (e.g., aqueous hydrofluoric acid having a concentration of about0.5 weight %, or dHF) for about 2 minutes. The trench structures 1100have a high aspect ratio (e.g., an aspect ratio of about 6 or more whenincluding the SiCN film 1102, and an aspect ratio of about 3 or morewhen not including the SiCN film 1102). The SiCN film 1102 had undergonepost film deposition plasma treatment, the plasma treatment usingreactant gases comprising hydrogen (H₂) and argon (Ar). As shown in FIG.12, the SiCN film 1102 comprises a continuous or substantiallycontinuous film in which distinct and separate layers are not visible.

The plasma treatment process of FIG. 12 can have one or more of theprocess parameters as described herein. For example, the plasmatreatment processes had a duration of about 30 minutes in which plasmawas turned on, performed using a plasma power of about 200 Watts (W), ata reactor chamber pressure of about 2 Torr and a susceptor temperatureof about 400° C., with the flow rate of H₂ at about 50 standard cubiccentimeters per minute (sccm), and the flow rate of Ar selected, forexample, to achieve the reactor chamber pressure of about 2 Torr duringthe plasma treatment process. The SiCN film can be formed according toone or more processes as described herein, for example using adeposition process having a SiCN sub-cycle percentage of about 80% and aBTCSEt as the precursor comprising silicon and carbon. The plasmatreatment process for providing the plasma treated SiCN film 1102 can beperformed after performing a number of complete cycles for depositing aSiCN film.

FIG. 12 shows that the SiCN film 1102 demonstrated excellentconformality to the underlying trench structures 1100, and a thicknessof about 26 nanometers (nm) remains on vertical sidewalls of individualtrenches of the trench structures 1100. For example, typically PEALDprocesses for forming a silicon nitride based film layer cannot achievedesired conformality to underlying three-dimensional (3-D) features.

In some embodiments, a SiCN film's resistance against removal fromwithin a 3-D structure can be similar to that from an open area. In someembodiments, the SiCN film's resistance against removal from within a3-D structure can be similar to or the same as that of a SiCN filmdeposited on a blanket wafer. For example, SiCN film deposited on ablanket wafer can demonstrate a remaining film thickness of about 26 nmafter being exposed to dHF for about 2 minutes, similar to or the sameas the SiCN film 1102 remaining on vertical sidewalls of individualtrenches of the trench structures 1100 shown in FIG. 12.

FIGS. 13 and 14 include tables providing additional X-ray photoelectronspectroscopy (XPS) analysis of various SiCN films formed according toone or more processes as described herein. For example, the “SiCN-1”films as listed in the tables of FIGS. 13 and 14 were formed usingBCTSMe as the precursor comprising silicon and carbon and a processhaving a SiCN sub-cycle percentage of about 80%. The “SiCN-2” films aslisted in the tables of FIGS. 13 and 14 were formed using BTCSEt as theprecursor comprising silicon and carbon and a process having a SiCNsub-cycle percentage of about 80%. The SiCN-1 and SiCN-2 films labeledas being subjected to a plasma treatment process were subjected to aplasma process using reactant gases comprising hydrogen (H₂) and argon(Ar). For example, the films underwent plasma treatment process having aduration of about 30 minutes in which plasma is turned on, performedusing a plasma power of about 200 Watts (W), at a reactor chamberpressure of about 2 Torr and a susceptor temperature of about 400° C.,with the flow rate of H₂ about 50 standard cubic centimeters per minute(sccm), and the flow rate of Ar selected, for example, to achieve thereactor chamber pressure of about 2 Torr during the plasma treatmentprocess (e.g., about 600 sccm). In some embodiments, the flow rate of Arcan be selected, for example, to achieve the reactor chamber pressure ofabout 2 Torr during the plasma treatment process. The plasma treatmentprocess can be performed after performing a number of complete cyclesfor depositing a SiCN film. The table of FIG. 13 shows measuredcompositions of the SiCN-1 and SiCN-2 films, expressed in atomic %,before and after being subjected to the plasma treatment measured, basedon both a sample having as-received sample surface (e.g., a samplesurface without or substantially without a surface cleaning process, forexample such that the sample surface may contain one or more atmosphericcontaminants), and a sample after 80 Å of sputtering (e.g., after 80 Åof each SiCN film was sputtered prior and/or removed from the filmsurface prior to conducting the XPS analysis for determining bulkcomposition). The table of FIG. 14 shows carbon (C) chemical state,expressed in atomic % C. The table of FIG. 14 shows atoms to whichcarbon in the film are bonded. The atomic % C of the table in FIG. 14adds up to equal or substantially equal the corresponding Cconcentration shown in the table of FIG. 13. As shown in FIGS. 13 and14, in some embodiments, the plasma treatment may advantageously notsignificantly change the film compositions. For example, the table ofFIG. 14 shows a difference of about 2 atomic % C—Si bonding to thesample surfaces after the H plasma treatment.

Although this disclosure has been provided in the context of certainembodiments and examples, it will be understood by those skilled in theart that the disclosure extends beyond the specifically describedembodiments to other alternative embodiments and/or uses of theembodiments and obvious modifications and equivalents thereof. Inaddition, while several variations of the embodiments of the disclosurehave been shown and described in detail, other modifications, which arewithin the scope of this disclosure, will be readily apparent to thoseof skill in the art based upon this disclosure. It is also contemplatedthat various combinations or sub-combinations of the specific featuresand aspects of the embodiments may be made and still fall within thescope of the disclosure. It should be understood that various featuresand aspects of the disclosed embodiments can be combined with, orsubstituted for, one another in order to form varying modes of theembodiments of the disclosure. Thus, it is intended that the scope ofthe disclosure should not be limited by the particular embodimentsdescribed above.

The headings provided herein, if any, are for convenience only and donot necessarily affect the scope or meaning of the devices and methodsdisclosed herein.

What is claimed is:
 1. A method for forming a plasma-treated film on asubstrate comprising: depositing a thin film on the substrate by aplurality of deposition cycles each comprising alternately andsequentially contacting the substrate with a first vapor-phase siliconprecursor comprising two silicon atoms bound to a hydrocarbon in anSi—R—Si— structure, where R comprises a C₁ to C₈ hydrocarbon, and asecond vapor-phase nitrogen reactant; and subsequently exposing thesubstrate to a hydrogen-containing plasma generated from a reactant gasthat comprises H₂, wherein a ratio of a wet etch rate of theplasma-treated film on the sidewall region of a three-dimensionalstructure to a wet etch rate of the treated thin film on the top regionof the three-dimensional structure is less than 3 as measured in adilute aqueous solution of hydrofluoric acid having a concentration of0.5 weight %.
 2. The method of claim 1, wherein the plasma-treated filmhas a wet etch rate that is less than about 50% of the wet etch rate ofthermal silicon oxide, as measured in dilute hydrofluoric acid having aconcentration of 0.5 weight %.
 3. The method of claim 1, wherein theplasma-treated film has a wet etch rate of less than about 1 nm/min in adilute aqueous solution of hydrofluoric acid having a concentration of0.5 weight %.
 4. The method of claim 1, wherein the plurality ofdeposition cycles are part of a thermal atomic layer deposition (ALD)process.
 5. The process of claim 1, wherein the thin film is depositedat a temperature of 300 to 600° C.
 6. The method of claim 1, wherein thereactant gas comprises a noble gas.
 7. The method of claim 6, whereinthe reactant gas comprises one or more of N₂, H₂ and Ar.
 8. The methodof claim 6, wherein the reactant gas consists of hydrogen gas (H₂) and anoble gas.
 9. The method of claim 1, wherein the thin film is exposed tothe hydrogen-containing plasma for at least 30 seconds.
 10. The methodof claim 9, wherein the thin film is exposed to the hydrogen-containingplasma for at least 10 minutes.
 11. The method of claim 1, wherein thehydrogen-containing plasma is generated by applying RF power from about100 W to about 500 W to the reactant gas.
 12. The method of claim 1,wherein exposing the thin film to the hydrogen-containing plasmacomprises a plurality of cycles in which the plasma is turned on for afirst duration of time and turned off for a second duration of time. 13.The method of claim 12, wherein the duration in which the plasma isturned on differs in two or more cycles.
 14. The method of claim 1,wherein the deposited thin film comprises carbon.
 15. The method ofclaim 1, wherein the nitrogen reactant comprises a hydrogen atom bondedto a nitrogen atom.
 16. The method of claim 1, wherein the nitrogenreactant is NH₃.
 17. The method of claim 1, wherein in the siliconprecursor R comprises a C₁ to C₃ alkyl chain.
 18. The method of claim 1,wherein the silicon precursor is a halogen substituted silylalkane. 19.The method of claim 1, wherein the silicon precursor comprises anunsubstituted silylalkane.
 20. The method of claim 19, wherein thesilicon precursor comprises bis(silyl)alkane, tris(silyl)alkane ortetrakis(silyl)alkane.
 21. The method of claim 1, wherein the siliconprecursor comprises bis(trichlorosilyl)methane (BTCSMe) or1,2-bis(trichlorosilyl)ethane (BTCSEt).